Most industrial plants of today are provided with control systems for controlling and monitoring of a plurality of functions, processes, production steps and the like via field devices comprising sensors, detectors, PLCs, control units, drive units etc. Thus a communication infrastructure needs to be present in the plant for enabling the data and information communication between the different field devices of the control system. The control systems aid the personnel responsible for the plant to ensure its operation and to optimize the process. In these types of systems often closed loop control is used, whereby the control system sends signals to for example a drive unit to change its motor speed, which motor speed is sensed by a sensor that sends a signal of the actual speed back to the control system.
The communication is enabled with industrial process control systems, such as for example the IT System 800xA from ABB. Such communication contains a wired fieldbus infrastructure where a large number of field devices can be connected and controlled. The system can utilize a number of field bus communication protocols such as Foundation, HART and Profibus.
During a number of years the trend in communication has been to go from wired to wireless communication systems, and there is a similar, but more recent, trend also in industrial process applications. A few wireless field devices and control units have been developed and also the process communication protocols have been developed to handle wireless communication.
Even if wireless communication in many applications simplify the setup of a process control system in that much less wiring is needed, and it is also less complicated to add field devices without having to fit new wiring in existing systems, wireless communication also place higher demands on the engineering tools & methods used for industrial automation applications. One aspect is that the wireless communication often is inferior to wired communication. There could be a number of interference and attenuation sources that may affect the quality of the wireless signals, resulting in packet loss, variable time delay, radio interference and other stochastic behaviour that will directly influence the quality and stability of the controlled processes. Thus, in order to take advantage of wireless communication systems between field devices and controllers, the stability of the end system has to be ensured. In order to do this the communication topology must be co-engineered with the 3-dimensional (3D) plant layout or topology and the control system.
This engineering task is very time-consuming and difficult due to the amount of communication and control theory involved and to the iterative nature of the problem.